[20220507]優化的困惑13.txt
[20220507]優化的困惑13.txt
--//生產系統一條sql語句,優化時遇到的問題,做一個記錄:
1.環境:
> @ pr
==============================
PORT_STRING : x86_64/Linux 2.4.xx
VERSION : 19.0.0.0.0
BANNER : Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
BANNER_FULL : Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.9.0.0.0
BANNER_LEGACY : Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
CON_ID : 0
PL/SQL procedure successfully completed.
2.語句如下:
--//sql_id=1br2zkb5wx8np.
SELECT gy_jbbm.jbxh,gy_jbbm.jbmc,gy_jbbm.icd9,gy_jbbm.pydm
FROM gy_jbbm
LEFT OUTER JOIN emr_xyjbbm
ON GY_JBBM.jbxh = emr_xyjbbm.jbxh
AND emr_xyjbbm.zxbz = 0
where (GY_JBBM.DMLB = 10)
AND ( (GY_JBBM.ICD9 LIKE '%齲病%' )
OR (GY_JBBM.JBMC LIKE '%齲病%' )
OR (GY_JBBM.PYDM LIKE '%齲病%' )
OR (EMR_XYJBBM.BMMC LIKE '%齲病%' )
OR (EMR_XYJBBM.PYDM LIKE '%齲病%' ) )
ORDER BY GY_JBBM.ICD9,GY_JBBM.JBMC,GY_JBBM.PYDM;
--//注:為了測試方便我直接帶入真實的值.
--//開啟統計後執行計劃如下:
Plan hash value: 3718689590
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows |E-Bytes|E-Temp | Cost (%CPU)| E-Time | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | | | 7277 (100)| | 4 |00:00:00.15 | 1385 | | | |
| 1 | SORT ORDER BY | | 1 | 152K| 30M| 32M| 7277 (1)| 00:00:01 | 4 |00:00:00.15 | 1385 | 2048 | 2048 | 2048 (0)|
|* 2 | FILTER | | 1 | | | | | | 4 |00:00:00.15 | 1385 | | | |
| 3 | NESTED LOOPS OUTER | | 1 | 152K| 30M| | 375 (1)| 00:00:01 | 152K|00:00:00.08 | 1385 | | | |
|* 4 | INDEX FAST FULL SCAN | I_GY_JBBM_ALL | 1 | 152K| 6863K| | 374 (1)| 00:00:01 | 152K|00:00:00.03 | 1385 | | | |
|* 5 | TABLE ACCESS BY INDEX ROWID BATCHED| EMR_XYJBBM | 152K| 1 | 162 | | 0 (0)| | 0 |00:00:00.02 | 0 | | | |
|* 6 | INDEX RANGE SCAN | IDX_EMR_XYJBBM_JBXH | 0 | 1 | | | 0 (0)| | 0 |00:00:00.01 | 0 | | | |
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - filter((("GY_JBBM"."ICD9" LIKE '%齲病%' AND "GY_JBBM"."ICD9" IS NOT NULL AND "GY_JBBM"."ICD9" IS NOT NULL) OR ("GY_JBBM"."JBMC" LIKE '%齲病%' AND "GY_JBBM"."JBMC" IS NOT NULL
AND "GY_JBBM"."JBMC" IS NOT NULL) OR ("GY_JBBM"."PYDM" LIKE '%齲病%' AND "GY_JBBM"."PYDM" IS NOT NULL AND "GY_JBBM"."PYDM" IS NOT NULL) OR "EMR_XYJBBM"."BMMC" LIKE '%齲病%' OR
"EMR_XYJBBM"."PYDM" LIKE '%齲病%'))
4 - filter("GY_JBBM"."DMLB"=10)
5 - filter("EMR_XYJBBM"."ZXBZ"=0)
6 - access("GY_JBBM"."JBXH"="EMR_XYJBBM"."JBXH")
--//補充說明,實際上這條sql語句沒有什麼好優化的,我建立I_GY_JBBM_ALL索引,覆蓋了gy_jbbm的全部顯示欄位.這樣一定程度不要全表
--//掃描gy_jbbm,減少一定的邏輯讀.奇怪的是id=2的FILTER出現在最後,如果你仔細看Predicate Information (identified by operation id):
--//可以發現oracle 自動加入了像如下條件兩遍:
"GY_JBBM"."ICD9" IS NOT NULL AND
"GY_JBBM"."ICD9" IS NOT NULL
--//不知道為什麼?實際上開始我並沒有認真看執行計劃,我開始想為什麼過濾(GY_JBBM.ICD9 LIKE '%齲病%' ) 不發生在id=4,而是出現在最後id=2.
--//這樣直接執行實際上"很慢"的,好在EMR_XYJBBM是一個沒有記錄的空表,不然id=5,starts=152K次,邏輯讀會很大.
--//我再次仔細看了sql語句.我個人並不喜歡ansi的語法,或者講更加喜歡使用+的語法,我以前經常改寫不知道那邊寫入+號.
--//我自己做了一個簡單記憶左連線 正好相反在 右邊的表使用+.
--//其實開發上面的寫法要非常小心,不小心很容易發生錯誤,參考連結:
--//http://blog.itpub.net/267265/viewspace-1988395/ => [20160213]關於ansi語法.txt
--//我想更多的是上面的寫法可能並不是開發想要寫法.或者講我認為開發寫錯了.
--//使用expandz.sql 展開看看。
$ cat tpt/expandz.sql
set long 40000
set serveroutput on
column arg new_value arg
set term off
select decode(&2,11,'sql2','utility') arg from dual;
set term on
prompt
declare
l_sqltext clob := null;
l_result clob := null;
begin
select sql_fulltext into l_sqltext from v$sqlarea where sql_id='&&1';
-- dbms_output.put_line(l_sqltext);
-- dbms_sql2.expand_sql_text(l_sqltext,l_result);
dbms_&arg..expand_sql_text(l_sqltext,l_result);
dbms_output.put_line(l_result);
end;
/
set serveroutput off
> @ cs PPPP_HHHH
alter session set current_schema=PPPP_HHHH
Session altered.
> @ expandz 1br2zkb5wx8np 19
SELECT "A1"."QCSJ_C000000000300000_0" "JBXH"
, "A1"."JBMC_2" "JBMC"
, "A1"."ICD9_4" "ICD9"
, "A1"."QCSJ_C000000000300002_3" "PYDM"
FROM (
SELECT "A3"."JBXH" "QCSJ_C000000000300000_0"
, "A3"."DMLB" "DMLB_1"
, "A3"."JBMC" "JBMC_2"
, "A3"."PYDM" "QCSJ_C000000000300002_3"
, "A3"."ICD9" "ICD9_4"
, "A3"."ZXBZ" "QCSJ_C000000000300004"
, "A2"."JBXH" "QCSJ_C000000000300001"
, "A2"."BMMC" "BMMC_7"
, "A2"."PYDM" "QCSJ_C000000000300003_8"
, "A2"."ZXBZ" "QCSJ_C000000000300005"
FROM "PPPPPP_HHH"."GY_JBBM" "A3"
, "PPPPPP_HHH"."EMR_XYJBBM" "A2"
WHERE "A3"."JBXH" = "A2"."JBXH"
AND "A2"."ZXBZ" = :B1) "A1"
WHERE "A1"."DMLB_1" = :B2
AND ("A1"."ICD9_4" LIKE :B3
OR "A1"."JBMC_2" LIKE :B4
OR "A1"."QCSJ_C000000000300002_3" LIKE :B5
OR "A1"."BMMC_7" LIKE :B6
OR "A1"."QCSJ_C000000000300003_8" LIKE :B7)
ORDER BY "A1"."ICD9_4"
, "A1"."JBMC_2"
, "A1"."QCSJ_C000000000300002_3"
PL/SQL procedure successfully completed.
--//注我做了格式化處理,可以發現展開後like在最後處理。另外還可以發現oracle展開後根本不存在外連線，為什麼不懂。
--//我帶入執行，沒有結果，很明顯展開是錯誤的。
SELECT "A1"."QCSJ_C000000000300000_0" "JBXH"
, "A1"."JBMC_2" "JBMC"
, "A1"."ICD9_4" "ICD9"
, "A1"."QCSJ_C000000000300002_3" "PYDM"
FROM (
SELECT "A3"."JBXH" "QCSJ_C000000000300000_0"
, "A3"."DMLB" "DMLB_1"
, "A3"."JBMC" "JBMC_2"
, "A3"."PYDM" "QCSJ_C000000000300002_3"
, "A3"."ICD9" "ICD9_4"
, "A3"."ZXBZ" "QCSJ_C000000000300004"
, "A2"."JBXH" "QCSJ_C000000000300001"
, "A2"."BMMC" "BMMC_7"
, "A2"."PYDM" "QCSJ_C000000000300003_8"
, "A2"."ZXBZ" "QCSJ_C000000000300005"
FROM "PPPPPP_HHH"."GY_JBBM" "A3"
, "PPPPPP_HHH"."EMR_XYJBBM" "A2"
WHERE "A3"."JBXH" = "A2"."JBXH"
AND "A2"."ZXBZ" = 0) "A1"
WHERE "A1"."DMLB_1" = 10
AND ("A1"."ICD9_4" LIKE '%齲病%'
OR "A1"."JBMC_2" LIKE '%齲病%'
OR "A1"."QCSJ_C000000000300002_3" LIKE '%齲病%'
OR "A1"."BMMC_7" LIKE '%齲病%'
OR "A1"."QCSJ_C000000000300003_8" LIKE '%齲病%')
ORDER BY "A1"."ICD9_4"
, "A1"."JBMC_2"
, "A1"."QCSJ_C000000000300002_3"
$ cat 10053x.sql
execute dbms_sqldiag.dump_trace(p_sql_id=>'&1',p_child_number=>&2,p_component=>'Compiler',p_file_id=>'a'||'&&1');
> @ 10053x 1br2zkb5wx8np 0
PL/SQL procedure successfully completed.
--//檢視跟蹤檔案：
Final query after transformations:******* UNPARSED QUERY IS *******
SELECT "GY_JBBM"."JBXH" "JBXH"
, "GY_JBBM"."JBMC" "JBMC"
, "GY_JBBM"."ICD9" "ICD9"
, "GY_JBBM"."PYDM" "PYDM"
FROM "PPPPPP_HHH"."GY_JBBM" "GY_JBBM"
, "PPPPPP_HHH"."EMR_XYJBBM" "EMR_XYJBBM"
WHERE "GY_JBBM"."DMLB" = :B1
AND ("GY_JBBM"."ICD9" LIKE :B2
OR "GY_JBBM"."JBMC" LIKE :B3
OR "GY_JBBM"."PYDM" LIKE :B4
OR "EMR_XYJBBM"."BMMC" LIKE :B5
OR "EMR_XYJBBM"."PYDM" LIKE :B6)
AND "GY_JBBM"."JBXH" = "EMR_XYJBBM"."JBXH"(+)
AND "EMR_XYJBBM"."ZXBZ"(+) = :B7
ORDER BY "GY_JBBM"."ICD9"
, "GY_JBBM"."JBMC"
, "GY_JBBM"."PYDM"
kkoqbc: optimizing query block SEL$2BFA4EE4 (#1)
--//你可以發現oracle實際上最後還是轉換成+的語法。
3.改寫:
--//首先我個人認為上面的寫法開發寫錯了.我使用加號改寫,注意可能不是等價的改寫!!
SELECT /*+ gather_plan_statistics */ gy_jbbm.jbxh
, gy_jbbm.jbmc
, gy_jbbm.icd9
, gy_jbbm.pydm
FROM gy_jbbm
, emr_xyjbbm
WHERE GY_JBBM.jbxh = emr_xyjbbm.jbxh(+)
AND emr_xyjbbm.zxbz(+) = 0
AND (GY_JBBM.DMLB = 10)
AND ( (GY_JBBM.ICD9 LIKE '%齲病%')
OR (GY_JBBM.JBMC LIKE '%齲病%')
OR (GY_JBBM.PYDM LIKE '%齲病%')
OR (EMR_XYJBBM.BMMC LIKE '%齲病%')
OR (EMR_XYJBBM.PYDM LIKE '%齲病%'))
ORDER BY GY_JBBM.ICD9 , GY_JBBM.JBMC , GY_JBBM.PYDM;
--//對比前面的10053x.sql看到，該語句是等價轉換。
--//執行計劃如下:
Plan hash value: 3718689590
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows |E-Bytes|E-Temp | Cost (%CPU)| E-Time | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | | | 7277 (100)| | 4 |00:00:00.13 | 1385 | | | |
| 1 | SORT ORDER BY | | 1 | 152K| 30M| 32M| 7277 (1)| 00:00:01 | 4 |00:00:00.13 | 1385 | 2048 | 2048 | 2048 (0)|
|* 2 | FILTER | | 1 | | | | | | 4 |00:00:00.05 | 1385 | | | |
| 3 | NESTED LOOPS OUTER | | 1 | 152K| 30M| | 375 (1)| 00:00:01 | 152K|00:00:00.08 | 1385 | | | |
|* 4 | INDEX FAST FULL SCAN | I_GY_JBBM_ALL | 1 | 152K| 6863K| | 374 (1)| 00:00:01 | 152K|00:00:00.03 | 1385 | | | |
|* 5 | TABLE ACCESS BY INDEX ROWID BATCHED| EMR_XYJBBM | 152K| 1 | 162 | | 0 (0)| | 0 |00:00:00.02 | 0 | | | |
|* 6 | INDEX RANGE SCAN | IDX_EMR_XYJBBM_JBXH | 0 | 1 | | | 0 (0)| | 0 |00:00:00.01 | 0 | | | |
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - filter((("GY_JBBM"."ICD9" LIKE '%齲病%' AND "GY_JBBM"."ICD9" IS NOT NULL AND "GY_JBBM"."ICD9" IS NOT NULL) OR ("GY_JBBM"."JBMC" LIKE '%齲病%' AND "GY_JBBM"."JBMC" IS NOT NULL
AND "GY_JBBM"."JBMC" IS NOT NULL) OR ("GY_JBBM"."PYDM" LIKE '%齲病%' AND "GY_JBBM"."PYDM" IS NOT NULL AND "GY_JBBM"."PYDM" IS NOT NULL) OR "EMR_XYJBBM"."BMMC" LIKE '%齲病%' OR
"EMR_XYJBBM"."PYDM" LIKE '%齲病%'))
4 - filter("GY_JBBM"."DMLB"=10)
5 - filter("EMR_XYJBBM"."ZXBZ"=0)
6 - access("GY_JBBM"."JBXH"="EMR_XYJBBM"."JBXH")
--//這時我才注意,裡面的一堆or.實際上開發要表達的是(我認為),應該之間的是and不是or.
--//我嘗試在EMR_XYJBBM表的欄位上寫入加號.(EMR_XYJBBM.BMMC(+) LIKE '%齲病%'),報如下錯誤：
ORA-01719: outer join operator (+) not allowed in operand of OR or IN
--//修改如下：
SELECT /*+ gather_plan_statistics */
gy_jbbm.jbxh
,gy_jbbm.jbmc
,gy_jbbm.icd9
,gy_jbbm.pydm
FROM gy_jbbm, emr_xyjbbm
WHERE GY_JBBM.jbxh = emr_xyjbbm.jbxh(+)
AND emr_xyjbbm.zxbz(+) = 0
AND (GY_JBBM.DMLB = 10)
AND ( GY_JBBM.ICD9 LIKE '%齲病%'
OR GY_JBBM.JBMC LIKE '%齲病%'
OR GY_JBBM.PYDM LIKE '%齲病%')
AND ( EMR_XYJBBM.BMMC(+) LIKE '%齲病%'
~~~
OR EMR_XYJBBM.PYDM(+) LIKE '%齲病%')
ORDER BY GY_JBBM.ICD9, GY_JBBM.JBMC, GY_JBBM.PYDM;
--//執行計劃如下:
Plan hash value: 1931007572
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows |E-Bytes|E-Temp | Cost (%CPU)| E-Time | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | | | 1319 (100)| | 4 |00:00:00.07 | 1385 | | | |
| 1 | SORT ORDER BY | | 1 | 20844 | 4233K| 4520K| 1319 (1)| 00:00:01 | 4 |00:00:00.07 | 1385 | 2048 | 2048 | 2048 (0)|
| 2 | NESTED LOOPS OUTER | | 1 | 20844 | 4233K| | 375 (1)| 00:00:01 | 4 |00:00:00.03 | 1385 | | | |
|* 3 | INDEX FAST FULL SCAN | I_GY_JBBM_ALL | 1 | 20844 | 936K| | 375 (1)| 00:00:01 | 4 |00:00:00.03 | 1385 | | | |
|* 4 | TABLE ACCESS BY INDEX ROWID BATCHED| EMR_XYJBBM | 4 | 1 | 162 | | 0 (0)| | 0 |00:00:00.01 | 0 | | | |
|* 5 | INDEX RANGE SCAN | IDX_EMR_XYJBBM_JBXH | 0 | 1 | | | 0 (0)| | 0 |00:00:00.01 | 0 | | | |
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
3 - filter(((("GY_JBBM"."JBMC" LIKE '%齲病%' AND "GY_JBBM"."JBMC" IS NOT NULL AND "GY_JBBM"."JBMC" IS NOT NULL) OR ("GY_JBBM"."PYDM" LIKE '%齲病%' AND "GY_JBBM"."PYDM" IS NOT
NULL AND "GY_JBBM"."PYDM" IS NOT NULL) OR ("GY_JBBM"."ICD9" LIKE '%齲病%' AND "GY_JBBM"."ICD9" IS NOT NULL AND "GY_JBBM"."ICD9" IS NOT NULL)) AND "GY_JBBM"."DMLB"=10))
4 - filter(("EMR_XYJBBM"."ZXBZ"=0 AND ("EMR_XYJBBM"."BMMC" LIKE '%齲病%' OR "EMR_XYJBBM"."PYDM" LIKE '%齲病%')))
5 - access("GY_JBBM"."JBXH"="EMR_XYJBBM"."JBXH")
--//我想這才是開發想要的執行方式。id=4的迴圈次數現在是starts=4.
--//或者講開發上面使用ansi的語法,"正確"的寫法如下:
SELECT /*+ gather_plan_statistics */
gy_jbbm.jbxh
,gy_jbbm.jbmc
,gy_jbbm.icd9
,gy_jbbm.pydm
FROM gy_jbbm
LEFT OUTER JOIN emr_xyjbbm
ON GY_JBBM.jbxh = emr_xyjbbm.jbxh
AND ( EMR_XYJBBM.BMMC LIKE '%齲病%'
OR EMR_XYJBBM.PYDM LIKE '%齲病%')
AND emr_xyjbbm.zxbz = 0
WHERE GY_JBBM.DMLB = 10
AND ( GY_JBBM.ICD9 LIKE '%齲病%'
OR GY_JBBM.JBMC LIKE '%齲病%'
OR GY_JBBM.PYDM LIKE '%齲病%')
ORDER BY GY_JBBM.ICD9, GY_JBBM.JBMC, GY_JBBM.PYDM;
--//執行計劃如下:
Plan hash value: 1931007572
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows |E-Bytes|E-Temp | Cost (%CPU)| E-Time | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | | | 1319 (100)| | 4 |00:00:00.07 | 1385 | | | |
| 1 | SORT ORDER BY | | 1 | 20844 | 4233K| 4520K| 1319 (1)| 00:00:01 | 4 |00:00:00.07 | 1385 | 2048 | 2048 | 2048 (0)|
| 2 | NESTED LOOPS OUTER | | 1 | 20844 | 4233K| | 375 (1)| 00:00:01 | 4 |00:00:00.03 | 1385 | | | |
|* 3 | INDEX FAST FULL SCAN | I_GY_JBBM_ALL | 1 | 20844 | 936K| | 375 (1)| 00:00:01 | 4 |00:00:00.03 | 1385 | | | |
|* 4 | TABLE ACCESS BY INDEX ROWID BATCHED| EMR_XYJBBM | 4 | 1 | 162 | | 0 (0)| | 0 |00:00:00.01 | 0 | | | |
|* 5 | INDEX RANGE SCAN | IDX_EMR_XYJBBM_JBXH | 0 | 1 | | | 0 (0)| | 0 |00:00:00.01 | 0 | | | |
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
3 - filter(((("GY_JBBM"."JBMC" LIKE '%齲病%' AND "GY_JBBM"."JBMC" IS NOT NULL AND "GY_JBBM"."JBMC" IS NOT NULL) OR ("GY_JBBM"."PYDM" LIKE '%齲病%' AND "GY_JBBM"."PYDM" IS NOT
NULL AND "GY_JBBM"."PYDM" IS NOT NULL) OR ("GY_JBBM"."ICD9" LIKE '%齲病%' AND "GY_JBBM"."ICD9" IS NOT NULL AND "GY_JBBM"."ICD9" IS NOT NULL)) AND "GY_JBBM"."DMLB"=10))
4 - filter(("EMR_XYJBBM"."ZXBZ"=0 AND ("EMR_XYJBBM"."BMMC" LIKE '%齲病%' OR "EMR_XYJBBM"."PYDM" LIKE '%齲病%')))
5 - access("GY_JBBM"."JBXH"="EMR_XYJBBM"."JBXH")
3.總結：
--//我個人比較喜歡+的語法，實際上我個人認為上面的寫法很容易寫錯，開發團隊應該統一使用的語法。
--//而且使用加號的語法理論上滿足大部分應用的需求，而且不容易出錯。
來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/267265/viewspace-2893172/，如需轉載，請註明出處，否則將追究法律責任。
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